Most forages in the United States and in western Europe are stored or preserved by one of two methods: by drying the forage and bailing or stacking thereof; or by storing in their original moist state under oxygen limiting conditions. In the first case, the forage crop is cut and allowed to rest in the field. The crop may be mechanically conditioned or raked into windows to further facilitate natural evaporation of the moisture contained therein. If the forage crop is baled or stored before the evaporation process has progressed enough, there are several problems that could result. The mechanical handling or baling equipment may not even handle the forage that is too heavy or wet from excessive moisture. If the crop is successfully stored or baled and stacked in an enclosure, the oxidative degradation and heat produced therefrom, in the presence of the aforementioned excessive moisture, could result in deterioration of proteins and other important nutrients in the crop or even could result in enough heat production to cause storage facilities to burn. The presence of excessive moisture can destabilize baled hay and forages also by inducing the natural molds which occur on the surface of any forage to grow. These molds may produce harmful toxins or may reduce the palatability of the crop. However, if the forage crop is subjected to drying conditions for too long a time, then other deleterious conditions may result. Most of the beneficial plant proteins and other important nutrients are stored in the leaves of forage crops. Excessive wilting, drying, and mechanical conditioning results in the loosening of the leaves and loss when the crops are baled or picked up from the field. The resulting stored forage will assuredly be inferior in nutritional quality due to the loss of the above nutrients.
In the case of forage crops stored in oxygen limiting environments, there are several conditions that may result in oxidative deterioration of the stored forage. During the filling of silos or other holding vessels for the containment of silages, there is often a period of time when the vessel is left uncovered or unsealed since silos often cannot be filled to completion in one day. During the fermentation which occurs in stored moist forages under oxygen limiting conditions, lactic acid is produced by microflora of the forages resulting in general preservation of most of the ensiled forage mass because of the acidification effect. However, at the surface(s) of the mass of the ensiled forage it is common to note very serious oxidative spoilage occurring due to increased exposure to air. Losses due to surface spoilage in silos can be very serious. Oftentimes several tons of ensiled crops are deemed useless and must be discarded.